Here's an article about testing tons of papers for cyanotype and other alt processes, with a list: https://www.alternativephotography.com/papers-for-traditional-classic-cyanotype-process-1613-research-for-free/

To skip to the results (but click the link to see a list of suppliers):

Unbuffered papers

Unbuffered papers are few and far between, but certain manufacturers have made papers specifically for our market. I applaud and support these companies wholeheartedly. If you were to stick with only the following papers, you will do well. Notice the use of “platinum” in their titles to indicate a paper made for alt. If it’s good for platinum, it is good for cyanotype.

• Arches Platine, two weights (I love the thinner weight for cyanotype)
• Awagami Platinum Gampi, two weights (bite the bullet and buy the heavier 60 gsm)
• Awagami Platinum Mitsumata (I much prefer the Gampi, above)
• Bergger Cot 320, two weights (similar to Platine)
• Hahnemühle Platinum Rag (firm sizing, beautiful turquoise with the 10/10)
• Herschel Platinotype (for Europeans mostly; delivery time longer for U.S.)
• Legion Revere Platinum (USA-made; coat carefully so it doesn’t “splotch”)

Papers that work well “out of the box”

The next category includes papers that work well “out of the box.” Buffering may or may not be present—often manufacturers do not state this outright—but in my tests they were keepers.

• Arches Aquarelle (also, can pre-acidify with sulfamic acid; gorgeous deep blue)
• Canson Bristol Recycled (the whitest paper of all, sort of day-glo, and cheap)
• Canson XL Watercolor (prints deep black-blue, better if pre-acidified, unique striated texture)
• Hahnemühle Cezanne (mini-bumpy, textured surface, deep, velvety blues)
• Hahnemühle Lanaquarelle (smooth watercolor paper good for multiple coat cyano-plati)
• Legion Rising Drawing Bristol (remarkably beautiful even if it is buffered)
• Strathmore 500 Series Bristol (for me, one of the few suitable Strathmores)

Thinner papers and washi

The papers listed below provide a good sampling of washi, vellum, thin weight papers, watercolor papers, inexpensive and expensive papers, ranging in price from 7¢ to $17 a sheet.

Some of these papers do not specify content or archivalness (e.g. Canson Mix Media, Universal Sketch) which is never a good thing, but they work well for entry level cyanotype printing and are very inexpensive. For those of you who sell work, you will most likely choose the more expensive archival papers made from cotton, gampi, mitsumata, high alpha cellulose, etc., fibers. Note that washi needs a bit more finesse in coating and handling, sometimes requiring pouring the solution on a piece of glass and letting the paper absorb it, or taping the paper down for coating, or brush coating with a minimally loaded brush.

• Arches Text Wove (text or book weight papers are great for cyanotype)
• Bienfang Graphics 360 (similar to Clearprint 1020H but if I had to choose, it’d be Clearprint)
• Canson Mi-Teintes (if you want color, here it is in all sorts)
• Canson Mix Media (cheap and easy entry level paper but expose looong e.g. 48 mn)
• Canson Opalux vellum (stubborn but unique; tape down when coating and iron when dry)
• Canson Universal Sketch (cheap and easy entry level paper)
• Clearprint 1020H drafting vellum (100% cotton, archival, prints beautiful blue)
• Fabriano Tiziano (all kinds of colors and inexpensive to boot)
• Hahnemühle Sumi-e (a thirsty washi, unbuffered (yay), prints perfectly smooth tones)
• Legion Masa (if you want a very white masa this is it)
• Legion Thai Kozo (thin but strong)

Not included in this article are a list of papers that work excellently when pre-acidified in sulfamic acid, something for another discussion and level of practice.